Akathisia is one of the most serious and worrisome side effects of certain medications. Akathisia is characterized by physical restlessness, along with an inner state of mental restlessness or agitation that is disturbing and occasionally intolerable to the subject. Patients with akathisia often pace or move about excessively, and may feel restless, or that their muscles are itching, or that they are jumping out of their skin. Akathisia is associated with an increase in jerky foot tremors using tremorographic readings. Patients with akathisia have an intermittent low frequency (<4 Hz) tremor that occurs most frequently when patients are seated, and predominantly involves their lower extremities, though other body regions are affected in some individuals. Increased muscles tonus in one patient with acute akathisia has been reported.
Diagnosing akathisia can be very difficult because the diagnosis often hinges on clinical interview. For example, there are clinical rating scales, such as the Barnes Akathisia Scale, that may be used to evaluate akathisia. These rating scales provide only a subjective measure that depends on clinician skill and experience in observing and eliciting information from the subject. Many patients have difficulty providing some of the critical information. Some patients, such as children, or those who are psychotic and disorganized, are often unaware of and/or unable to describe medication side effects.
Actigraphs have been attached to subjects' ankles to record fluctuations in their level of ambulatory motor activity over a minimum of twenty-four continuous hours. Akathisia was associated with alterations in the pattern of circadian activity, although the activity measures were more strongly influenced by the nature of the patients' underlying psychiatric disorder that the degree of akathisia. Alterations in the pattern of circadian activity have been observed in schizophrenic patients with akathisia wearing actigraphs on their ankles. However, actigraphs worn on the ankle provide information about akathetic movement in the lower extremity only. While this is the most common site of akathetic movements, such movements may occur exclusively in other body parts, such as the head.
The medications that are known to produce akathisia as a side effect include antipsychotic or neuroleptic medications, some antidepressants, particularly the selective serotonin reuptake inhibitors, and the more noradrenergic tricyclic antidepressants, such as desipramine. Akathisia is the major reason for medication noncompliance, and has been linked to episodes of aggression, violence, and self-destructive behavior. However, given the difficulty in diagnosing akathisia, clinicians may attribute the deterioration in the patient's state to a worsening of his or her underlying psychiatric disorder. This misdiagnosis may lead to an increase in medication dose, which exacerbates rather than ameliorates the problem. Moreover, most attempts to diagnose akathisia focus exclusively on the physical aspect of akathisia.
There remains a need for methods of diagnosing the presence, type, or severity of akathisia in a subject. There is also a need for a method of diagnosing akathisia that can be preformed on the order of minutes, rather than hours.